108 AGRICULTURAL BACTERIOLOGY 



and the porosity of manures from the horse and sheep 

 permit the introduction of air, and hence favor the growth 

 of aerobic organisms, especially molds. The respiration of 

 the aerobic forms results in the production of heat, which 

 is not readily radiated on account of the non-conductivity 

 of the organic matter. As the temperature increases the 

 more rapid growth of the organisms is made possible. This 

 growth continues until the decomposition of the manure is 

 complete and the loss of nitrogen and organic matter is 

 marked. These so-called hot manures are subject to fire- 

 fanging. The loss of organic matter can be prevented by 

 the close packing of the piles to exclude air, or by the ad- 

 dition of water. In the absence of the air the decomposition 

 will be due to anaerobic forms, and while the rotting will be 

 complete in that the vegetable matter loses its identity, 

 there is not so great a loss as under aerobic conditions. 



Cow and hog manure are cold manures on account of 

 their high moisture content and their close texture, giving 

 no opportunity for air to penetrate. These manures do 

 not overheat or fire-fang. In two piles of manure of the 

 same composition, one of which was piled loosely while the 

 other was closely packed, the following losses were noted. 

 The loss of nitrogen from the loose pile amounted to 34 

 per cent, and the loss of organic matter to 53 per cent., 

 while from the closely packed pile the loss of nitrogen was 

 28 per cent, and of organic matter the same. 



The conservation of the fertilizing value of manures in- 

 volves the stopping of the processes of decomposition short 

 of completion. The last steps in decomposition are, as has 

 been mentioned, always due to aerobic organisms. The an- 

 aerobic organisms will disintegrate the fibrous materials of 

 the manure and enable it to be easily distributed over the 

 soil. In 'the anaerobic processes a considerable portion of 

 nitrogen, phosphorus, potassium, and sulphur in the ma- 



